The present invention relates generally to the field of vibrating conveyors, and in particular to parts feeders for feeding electronic components to "pick and place" machines which automatically surface mount such components on, for example, a printed circuit board.
The assembly of surface mounted printed circuit boards requires the placement of a wide variety and large number of small electronic components on the surface of the board in precisely located, predetermined positions. The repetitive nature of this task has led to the development of computer controlled, automatic "pick and place" machines which pick electronic components from a "pick" station, move the component to the printed circuit board, and "place" the component at a precisely defined, predetermined location on the circuit board.
To maintain a steady supply of components at the "pick" station, like components are packaged in elongate, open ended tubes. A plurality of tubes, each containing different components, are mounted on a vibrating feed tray such that the components are advanced out of the tubes. In order to guide the components to their respective "pick" station, channels or troughs must be provided on the tray. These channels or troughs must be properly dimensioned so as to ensure that the components are oriented in a predictable fashion upon arrival at the "pick" station.
Vibration of the tray causes the components to advance toward the end of the tray. Arriving at the end of the tray, the components butt against a stop plate, and is held in position until it is subsequently lifted from the tray. The continued vibration of the tray, after a component has arrived at the "pick" station and a plurality of components lined up within the trough behind it, has a tendency to disrupt the orientation of these components, and can cause them to be canted so as to stand up on end, as opposed to laying flat, as shown in FIG. 4. Such canting, sometimes called "tombstoning," can prevent the component from being lifted from the tray or if it is lifted, it will not be properly placed on the printed circuit board.
Accordingly, there is a need in the art for an apparatus which would ensure and maintain proper orientation of the components as they travel down the troughs and arrive at their respective "pick" station.